1. Technical Field
This invention relates to a balloon control apparatus and in particular to a balloon control apparatus that can eliminate (or lessen) difference in time until the balloon internal pressure reaches a predetermined pressure (namely, the time until the balloon is fixed) regardless of the type of digestive tract.
2. Description of the Related Art
Hitherto, in the field of an endoscope, the following endoscope with a balloon has been known. That is, from the viewpoint of fixing to a body cavity an endoscope insertion section (or an insertion aid instrument for guiding insertion of the endoscope insertion section) inserted into the body cavity, the endoscope has the balloon, which is expanded by air supply and contracted by exhaust, in the endoscope insertion section (or the insertion aid instrument; see JP 2002-301019 A and JP 2004-337288 A).
In the endoscope with the balloon, an air pump is connected to the balloon via a tube, etc.
As an air supply (pressurizing) switch is turned on, the air pump starts air supply, whereby the balloon starts to expand. After a while, the balloon expands and contacts an intestinal wall, etc., and the balloon internal pressure reaches a predetermined setup pressure.
Thus, when the balloon internal pressure reaches the predetermined setup pressure (for example, 5.6 kPa), the air pump is controlled so as to stop air supply.
On the other hand, as an exhaust (decompression) switch is turned on, the air pump starts exhaust, whereby the balloon starts to contract. After a while, the balloon contracts and the balloon internal pressure reaches a predetermined setup pressure.
Thus, when the balloon internal pressure reaches the predetermined setup pressure, the air pump is controlled so as to stop exhaust.
By the way, digestive tracts differ in diameter from one type to another (for example, a small intestine is about 25 mm in diameter and a large intestine is about 35 mm in diameter). Nevertheless, in the endoscope with the balloon according to the related art, air supply to the balloon or exhaust from the balloon is executed at a predetermined flow rate. Thus, the time required until the balloon expands and contacts an intestinal wall and the balloon internal pressure reaches a predetermined pressure varies from one digestive tract to another. For example, according to an experiment carried out by the inventor (assuming that the average diameter of a small intestine is about 25 mm and the average diameter of a large intestine is about 35 mm, air was supplied to a balloon placed in each intestine at a predetermined flow rate), the time required until the balloon expands and contacts the intestinal wall and the balloon internal pressure reaches a predetermined pressure was about 10 seconds for the small intestine and about 30 seconds for the large intestine.
Thus, in the endoscope with the balloon according to the related art, since air supply to the balloon (or exhaust from the balloon) is executed at a predetermined flow rate, the time until the balloon internal pressure reaches a predetermined pressure (namely, the time until the balloon is fixed) varies depending on the type of digestive tract, and the ease of operation is poor.